The present invention relates to a system for carding textile fibres.
The basic purpose of carding operations consists of dividing the flock of fibres into a uniform layer in which the fibres are separated, straightened and spread out in a single direction. The production of a web with a uniform distribution of fibres, with fibres which are sufficiently straight and with a uniform appearance and mixture of colours generally requires a system composed of many complex and large machines.
In particular, in some carding areas, it is necessary to have two or more carding machines in series with one another, between which there is a device which mixes the fibres to be supplied to the second carding machine in order to reduce errors due to a non-uniform distribution of the fibres both longitudinally and transversely in the web emerging from the first carding machine.
A typical method of mixing the fibres between the first and second carding machines consists of the provision of a layering device which forms a sliver composed of a plurality of superimposed layers produced from the web of fibres coming from the first carding machine. The sliver formed by the layering device is supplied to the second carding machine by means of a series of conveyors which change the arrangement and the orientation of the fibres supplying the second carding machine. The layering device and the conveyor constitute a layering system which can form a mat of fibres for supply to the second carding machine.
A problem which arises in carding systems with two carding machines in series with one another and a layering system interposed between the two carding machines is that the behaviour of the layered mat when it enters the second carding machine is unpredictable and non-uniform. There is a tendency to generate a non-uniform and repetitive distribution of fibres on the members of the carding machine in the second carding machine, and this involves the need to use a very complex carding machine having a large number of carding members with several drums to make up for the errors and the non-uniform distribution of the fibres.
In particular, a defect which occurs especially when the orientation of the fibres at the input of the second carding machine is predominantly transverse the direction of advance of the mat consists of the fact that "lumps" or tufts of fibres are torn from the supply sliver at the input to the second carding machine and give rise to irregular formations of fibres known as "flashing" on the carding drums. To eliminate these defects, it is necessary to subject the web to successive passes through carding cylinders and drums and, as well as increasing the complexity of the carding machines, this involves an increase in the time spent by the fibres inside the carding machine which increases the danger of damage to the fibres due to shortening thereof which causes severe depreciation of the most valuable fibres.